Chances are you're aware that the immune system is crucial for overall wellness, especially during times of the year when allergies, viruses, and bacterial infections are at their peak. However, you might not know that the integrity and function of the immune system can be significantly altered by what you eat.
For example, there are foods that may weaken the immune system over time by inducing low-grade inflammation and negatively affecting the gut microbiome (R). Such dietary culprits include excess sugar intake, soybean oil, refined grains, and hydrogenated fats (R).
On the contrary, there are certain foods/nutrients that support both innate and adaptive immunity, thereby aiding your body's ability to overcome things like the common cold and seasonal allergies (R).
While there is no particular diet or supplement that will prevent you from getting sick, making smarter choices about what you put in your body sets the foundation for a resilient immune system.
If there's any certainty in nutritional science, it's that antioxidant-rich food sources are generally good for longevity and wellness (R, R). Research continually shows that people who consume at least five servings of vegetables and/or fruits per day are at a significantly lower risk of a myriad of diseases, not to mention they have longer lifepsans (R).
So, which foods vegetables and fruits score as the cream of the crop (no pun intended) for immune health and overall wellness? Let's take a look at what science has to say!
Berries, especially wild blueberries, raspberries, acai berries, and blackberries, are Mother Nature's richest source of anthocyanins - a novel class of polyphenol antioxidants that have been shown to reduce inflammation and modulate genetic signalling in a beneficial manner (R). Even better, most berries contain a generous amount of dietary fiber and are relatively low in sugar compared to other fruits.
All varieties of beans are great sources of antioxidants, but kidney beans take the cake as being the most micronutrient-dense bean of all. Just a half cup of cooked kidney beans packs over 50% of the recommended daily intake (RDI) of dietary folate.
Studies have found that folate deficiency weakens resistance to infectious agents, ostensibly by disrupting cell cycle progression and inhibiting the production of white blood cells (R, R). Not to mention that folate deficiency is implicated in a handful of other deleterious health conditions (R).
Artichokes are one of the most healthful plant foods you're probably not eating. Due to their abundance of luteolin, a flavonoid that has been shown to inhibit antigens in the body, artichokes deserve an honest chance if you're looking for immune-boosting foods (R). Yes, they are an acquired taste; but hey, eating a few artichokes from time to time beats being under the weather.
Pumpkin is arguably the most under-appreciated plant food. While most of us think of pumpkin as being the main ingredient in pumpkin pie, it's actually a nutritional powerhouse with an immense amount of beta-carotene (vitamin A) and dietary fiber. In fact, one cup of pumpkin puree contains a whopping 300% of the RDI of vitamin A!
Research suggests that vitamin A deficiency compromises immune function by hindering antibody-mediated responses to invasive challenges (R). Now you have some good use for all the innards next time pumpkin carving season comes around.
Yogurt is made by fermenting milk products with bacterial starter cultures, such as Lactobacillus acidophilus. Greek yogurt goes an extra step by straining regular yogurt, yielding much higher protein content and a lower amount of sugar. Hence, Greek yogurt is a solid source of probiotics ("friendly bacteria") that help protect your immune system and fortify the gut microbiome (R).
Nuts and nut butter such as almonds/almond butter, cashews/cashew butter, macadamia nuts, etc., are all dense sources of essential fatty acids, notably monounsaturated fatty acids that protect the heart and micronutrients like vitamin E, which has been well-established in the literature to stimulate the body’s defense against infectious disease (R).
It appears that vitamin E does this by enhancing a process called phagocytosis, whereby a cell engulfs and digests a microbe or other foreign substance, effectively neutralizing it.
For reference, a serving (28 g) of raw almonds - roughly a small handful - provides upwards of 200% of the RDI of vitamin E. So, if you're looking for a reason to "go nuts," this is it.
In addition to eating more of the foods mentioned above, there are a handful of evidence-based nutritional supplements to consider for taking your health and wellness to the next level:
Pro-vitamin D3 (7-dehydrocholesterol) is essentially the "storage form" of vitamin D in the body and is particularly abundant in the epidermis (R). Upon exposure to the ultra-violet rays of sunlight, it is converted to vitamin D3 (cholecalciferol), which subsequently gets converted to bioactive vitamin D (calcitriol) on an as-needed basis.
Calcitriol goes onto play a crucial role in the immune system by modulating the innate immune response to pathogens (R). Given that many people live "indoor" lifestyles and don't get much sun exposure, vitamin D deficiency is on the rise (R).
The good news is that supplemental vitamin D3 has been used with promising results in a range of clinical studies, one of which found it was effective for preventing the development of autoimmune diseases, such as inflammatory bowel disease (R, R).
The catch is that vitamin D3 appears to work synergistically with magnesium in the body, as research shows they operate in a co-dependent fashion (R).
If you're lacking magnesium, your body won’t be able to efficiently convert vitamin D3 to bioactive calcitriol; if you lack active vitamin D, your body won’t be able to properly absorb magnesium.
The gut is home to an estimated 1,000+ microbial species (predominantly bacteria) that serve as commensal organisms - meaning they help us but we don't do much for them (R). While the precise roles of the gut microbiome remain somewhat misunderstood, there is overwhelming evidence that "good" bacteria are essential to immune function (R). In fact, upwards of 60% of the immune system derives from the gut.
Intuitively, taking care of your gut health with prebiotic greens (e.g. chlorella and spirulina) is arguably one of the best supplemental approaches to boosting immune function.
Well, in short, prebiotic greens nourish the "friendly" bacteria in the gut with dietary fibers that are able to ferment to short-chain fatty acids and gases (R). In turn, these bacteria are able to flourish while we reap the benefits of their metabolic byproducts. Pretty neat, wouldn't you say?
A recent meta-analysis concluded that curcumin - the primary constituent in turmeric root - may alleviate joint pains/aches, reduce inflammation, and support immunity (R). Given its versatility and safety profile, curcumin is becoming increasingly popular as a natural remedy for many inflammatory conditions, particularly rheumatoid arthritis.
The key when taking a turmeric supplement is to find one that has a standardized amount of curcumin (and other curcuminoids), plus black pepper fruit extract (piperine) for enhancing the absorption of curcumin through the liver.
Unlike conventional fish oil supplements, krill oil provides easy-to-absorb omega-3 essential fatty acids, notably eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in phospholipid form. Both EPA and DHA are reputed as being vital nutrients that support cardiovascular function, joint health, and immunity (R).
Krill oil is also a good source of choline and astaxanthin. Choline is an integral B vitamin that is necessary for phospholipid synthesis and the production of acetylcholine. As such, choline plays a pivotal role in cognitive function and protecting against neurodegeneration (R).
Astaxanthin complements choline by serving as a potent antioxidant that reduces phospholipid oxidation and works synergistically with omega-3s to support healthy blood lipid levels (R).